The invention relates to a methane conversion rate quantitative analysis and gas collection experimental device used during flare discharge. The methane conversion rate quantitative analysis and gas collection experimental device comprises an experimental rack, a natural gas steel cylinder, a high-purity nitrogen steel cylinder, a combustion frame, a gas collection cover and a vacuum micro-pump. The experimental rack is in an architecture design, and the natural gas steel cylinder, the high-purity nitrogen steel cylinder, the combustion frame, the gas collection cover and the vacuum micro-pumpare fixed onto the experimental rack. The natural gas steel cylinder is connected with the combustion frame by a gas flow meter I; the high-purity nitrogen steel cylinder is connected with the combustion frame by a gas flow meter II; the gas collection cover is arranged above a nozzle of the combustion frame, and the top of the gas collection cover is connected with a suction end of the vacuum micro-pump; an exhaust pipe and a gas collection bag are connected with a gas outlet end of the vacuum micro-pump, and the gas collection bag is connected with a constant-volume communicating vessel anda quantitative gas chromatograph. The methane conversion rate quantitative analysis and gas collection experimental device has the advantages that as proved by simulation experiments, the methane conversion rate quantitative analysis and gas collection experimental device is high in methane recovery, methane gas can be effectively collected during flare discharge to be used as an intermediate vector for field collected data and theoretical computational data, and accordingly possible measured deviation due to various uncertain factors in field detection procedures can be prevented.